This is a good alternative to the "Tennis Twist" or having some you underhand toss you balls to hit...

I bought a "baseball trainer/pitchback from Target for $20.

What I do is set it up an a slight angle on the service line, grab a bucket of balls and I stand on the baseline about 20 feet away and I throw balls at the rebounder and then hit them after one bounce. Its exactly like someone tossing them underhand to you. After a while you get good at hitting the rebounder in the right spot to give you a nice bounce back. I was surprised at how well it worked. Much better than hitting against a wall! I am using it to practice my 2HBH and I hit about 150 backhands tonite in about an hour and got a good workout.

Next time I'll try and take some video to better show how this works.

edit: I had to tilt the trainer a little more upwards to get the right bounce angle, so I just stuck a box under the bottom bar to raise it up about 1 foot.

You cannot hit a groundstroke to the rebounder like a wall and keep the ball going?